Special Kahler manifolds

We,give an intrinsic definition of the special geometry which arises in glo bal N = 2 supersymmetry in four dimensions. The base of an algebraic integr able system exhibits this geometry, and with an integrality hypothesis any special Kahler manifold is so related to an integrable system. The cotangen t bundle of a special Kahler manifold carries a hyperkahler metric. We also define special geometry in supergravity in terms of the special geometry i n global supersymmetry.